1. Field of the Invention
The invention relates to a drive force output apparatus, a method for controlling a drive force output apparatus, and a vehicle.
2. Description of the Related Art
Japanese Patent Application Publication No. 2003-47108 (JP-A-2003-47108) describes a drive force output apparatus having a drive motor, a power generator that generates power using the drive force of an engine, an inverter that drives the drive motor and the power generator, and a nickel metal hydrogen battery that exchanges power with the inverter, and the drive force output apparatus. This drive force output apparatus controls the engine, the power generator, and the drive motor so as to output a target torque set based on the operation by the driver while ensuring that the SOC (State Of Charge) level of the battery changes within a predetermined control range referenced at a target SOC level that is set within a proper SOC range. According to this drive force output apparatus, when a memory effect of the battery is detected, the target SOC level is changed so as to eliminate the memory effect.
A drive force output apparatus of this kind is also described in Japanese Patent Application Publication No. 2005-212595 (JP-A-2005-212595) which has an engine, a first motor, a drive force distribution mechanism connected to the engine and to the first motor, a second motor, and a transmission that transmits drive force from the second motor to a drive shaft while changing the speed ratio, a battery that exchanges power with the first and second motors, and an auxiliary electrically connected to the battery. According to this drive force output apparatus, if the power consumption of the auxiliary exceeds the output limit of the battery during the shifting of the transmission, the operation of the auxiliary is limited so as to avoid excessive discharge of the battery.
In general, drive force output apparatuses of this kind involve a difficulty in properly monitoring and controlling the SOC level of the battery. Thus, the target SOC level needs to be properly changed even if any memory effect has not been detected.
With regard to drive force output apparatuses of this kind, further, when it is required for the second motor to output relatively large torque, it is necessary to secure a sufficient amount of power for satisfying the torque output requirement. In this case, one option is to limit the power used for the auxiliary. However, how to limit the power for the auxiliary in such a case is still a pending issue.